<template>
  <div class="pagination">
    <!-- 上 -->
    <button :disabled="pageNo==1" @click="upPageNo">
      上一页
    </button>
    <button v-if="startNumAndEndNum.start>1" @click="changePage(1)" :class="{active:pageNo==1}">
      1
    </button>
    <button v-if="startNumAndEndNum.start>2">···</button>
    <!-- 中间部分 -->
    <button v-for="(page,index) in startNumAndEndNum.end" :key="index" v-if="page>=startNumAndEndNum.start"
      @click="changePage(page)" :class="{active:pageNo==page}">
      {{page}}
    </button>

    <!-- 下 -->
    <button v-if="startNumAndEndNum.end<totalPage-1">...</button>
    <button v-if="startNumAndEndNum.end<totalPage" @click="changePage(totalPage)" :class="{active:pageNo==totalPage}">
      {{ totalPage }}
    </button>
    <button :disabled="pageNo==totalPage" @click="onPageNo">
      下一页
    </button>
    <button style="margin-left: 30px">共 {{ total }} 条</button>
  </div>
</template>

<script>
  export default {
    name: "Pagination",
    props: ['pageNo', 'pageSize', 'total', 'countinues'],
    data() {
      return {}
    },
    methods: {
      upPageNo() {
        this.$emit("getPageNo", this.pageNo - 1)
      },
      changePage(val) {
        this.$emit("getPageNo", val)
      },
      onPageNo() {
        this.$emit("getPageNo", this.pageNo + 1)
      }
    },
    computed: {
      totalPage() {
        return Math.ceil(this.total / this.pageSize)
      },
      startNumAndEndNum() {
        let start = 0,
          end = 0
        if (this.continues > this.totalPage) {
          start = 1
          end = this.totalPage
        } else {
          if (this.pageNo < 3) {
            start = 1
            end = this.countinues
          } else if (this.pageNo > this.totalPage - parseInt(this.countinues / 2)) {
            start = this.totalPage - this.countinues
            end = this.totalPage
          } else {
            start = this.pageNo - parseInt(this.countinues / 2)
            end = this.pageNo + parseInt(this.countinues / 2)
          }
        }
        return {
          start,
          end
        }
      }
    }
  }
</script>

<style lang="less" scoped>
  .pagination {
    text-align: center;

    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }

  .active {
    background: skyblue;
  }
</style>
